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W'ILLARD E. CASE, OF AUBURN, NETV YORK.

PROCESS OF MAKING ELECTRODES FOR SECONDARY BATTERIES.

SPECIFICATION forming part of Letters Patent No. 309,293, dated December16, 1 884.

Application filed April 93, 1884.

To all ugh/m, it may concern;

Be it known that I, WILLARD E. CASE, of

Auburn, Cayuga county, New York, have invented a new and useful Processof Making Electrodes for Secondary Batteries, of which the following isa specification.

The invention relates to a process of making that class ofsecondary-battery electrodes of making the electrodes by melting thematerial and stirring it while cooling in avessel maintained in certainuniform temperature by steam, and then molding said electrodes.

In United States Patent No. 289,386, granted to me December 4, 1883, Ihave fully set forth my process of making electrodes by melt ing asuitable material and then stirring the same while cooling, to render itporous, and to enable it to present a large active surface, and finallyforming it into shape in molds; and in United States Patent No. 292,469,granted to me January 29, 1882, I have described a process of melting asuitable material and stirring in other substances, and then molding, towhich patents I refer as fully explaining examples of the classes ofelectrodes to which this invention is intended more particularly torelate.

I have found by experiment that when a suitable material forconstituting an electrode, to be made as above set forth-as, forexample, lead or a lead alloyis melted in a ladle directly over a fire,several disadvantages and difficulties become manifest.

First. The material is very apt to become overheated, often considerablybeyond its melting-point. To bring it to the proper viscid state formolding while on the fire by simply stirring it necessitates aconsiderable waste of time. 9

Second. If other ingredients are to be added, the too hot material mayinjure them-as, for example, if mercury is to be introduced, as is (Nospecimens.)

lating around it.

done in the process set forth in my Patent No. 292,469, that metal isvery apt to become vaporized by the high temperature, and so wasted,besides exposing the operator to the effects of its deleterious fumes.

Third. It is not possible to regulate the term perature of the moltenmaterial with an y eertainty when over the fire. The lower part of thecrucible is apt to be hotter than the upper part, and the material maybe of unequal consistence, so that the uniform dissemination through itof other ingredients may thus be retarded or prevented.

. Fourth. WVhen the crucible is removed from the fire and the materialthen stirred, it cools more rapidly, but without uniformity. The portionnearest the outside of the crucible may become partially solidified andstick to the sides while the inner portion is still liquid or,

nearly liquid. This greatly increases the laher of stirring, and alsoprevents uniform dissemination of the added ingredients. N ow, in makingsolid electrodes for storage-batteries, it is exceedingly important thatthey should be uniformly porous throughout, and filled with as manyminute pores as possible; and if other ingredients than that originallymelted are contained, it is-also important that these ingredients shouldbe distributed uniformly throughout the mass. \Vhen this is not thecase, the full efficiency of such an electrode cannot be gained.

In order to overcome the above-mcntioned difficulties, I have devisedthe following process: I first melt the material in the ordinary wayin aladle or crucible overafire. As soon as it is melted I turn it out intoa vessel of any desired form or construction, which is provided with ajacket or surrounded with a coiled pipe through which steam orsuperheated steam is caused to circulate. The arrangement andconstruction of this apparatus are not material so long as they be suchthat the inner vessel may receive heat from the steam circu- By means ofthe steam,the

supply of which may be regulated by a suitable hand-valve or by anyapparatus operating automatically to shut off the steam when a certaintemperature is attained, I heat the inner vessel as nearly as possibleto the tem perature of the material to be treated when it shall havecooled down to a pasty or viscid state. This can easily be found bysimply measuring the temperature of a sample of the material melted, andthen cooled as stated. When the molten material is introduced into thevessel, it is stirred, and as it is stirred it cools; but, by reason ofthe temperature of the vessel, it is not permitted to solidify or tocool down below or much below the pasty state. It follows, then, thatthe stirring-process can be efficiently and rapidly done, and that asthe material is maintained through out at a uniform temperature and in auniform state, all parts of it will be equally affected, and if otheringredients be added they can be completely incorporated with it. Afterthe stirring process is finished, I press the material or thecomp0und,while hot, in molds. I

1 do not cast it in the sense of running it into a mold and allowing itto assume permanent form by natural solidification. It is'essential thatthe material should be put into the molds in a hot or pasty state, and,while so hot and pasty, that it should be pressed into form.

When the electrodes are made in the manner above described, theirstructure is very homogeneous, and any tendency they may have to crumbleor break in the battery by use is reduced to a minimum.

I claim as my invention-- 1. The process of making electrodes forsecondary batteries, consisting in first melting the material of whichthe electrode is to be composed; second, cooling said material in avessel heated by steam at or near the temperature of said material whilein a pasty or viscid state, and stirring said material in said vesselwhile cooling until it reaches said viscid state; third, pressing saidmaterial, while in said viscid state, in form in a suitablemold ormolds, substantially as described.

2. The process of making electrodes for secondary batteries, consistingin first melting a material which the electrode is to contain; second,cooling said material inavessel heated by steam at or near thetemperature of said material while in a pasty or viscid state, stirringsaid material in said vessel while 'cooling until it reaches said viscidstate, and at the same time adding any other ingredient or ingredientswhich it is desired to combine With said material; third, pressing saidcompound,while in said viscid state, in form in a suitable mold ormolds, substantially as described.

WILLARD E. CASE.

Vitnesses:

\V. A. FRENCH, F. XV. SMITH.

